…ney/build-upgrades

…ney/build-upgrades

- Use regex with negative lookahead in generate_diagrams.py to avoid
  mutating multi-digit stroke-width values (e.g., stroke-width:10)
- Remove neo4j tutorial (not part of this PR per reviewer)
- Update data-setup tutorial to document --data-dir CLI option
- Update pregel and motif tutorial docs to use data_dir path pattern

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

Commit ec1b084 accidentally removed the connected components diagram
from the Connected Components section of the Pregel tutorial. The SVG
file exists at docs/src/img/pregel-diagrams/pregel-connected-components.svg
and should be shown like all other example sections in the tutorial.

The original commit was mislabeled as removing a 'Mermaid diagram' but
actually removed a rendered SVG <img> tag.

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

The connected-components SVG renders with only 2 nodes and 0 edges
(broken Mermaid render), making it useless in the tutorial. Reverting
the prior mistaken restore; the image reference should remain absent
from the Connected Components section.

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

…syntax

Chained undirected edges (A --- B --- C) fail to render in LR layout
with some Mermaid versions, producing a broken SVG with only 2 nodes.
Fix by using explicit two-node edge lines instead.

Also restore the connected-components diagram in the docs tutorial
(04-pregel-tutorial.md) which was previously removed due to the broken
SVG. With the correct rendering (18 nodes, 3 supersteps), the diagram
is now suitable for the tutorial.

Update generate_diagrams.py to use the fixed Mermaid syntax with a
comment explaining the workaround.

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

In Jupyter notebooks and docs, <figcaption> rendered as unstyled
block text indistinguishable from surrounding headings/paragraphs.

- Add a <style> block at the top of each notebook's first markdown
  cell to globally apply caption styling (smaller, italic, grey,
  centered) via the figcaption CSS selector
- Add equivalent inline style attributes to every <figcaption> in
  the Laika docs markdown files (04-pregel-tutorial.md and
  02-motif-tutorial.md) for the static site build

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

These SVG files were accidentally generated by running generate_diagrams.py
from the python/ working directory (causing relative output path to resolve
as python/docs/src/img/ instead of docs/src/img/).

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

Replace relative 'docs/src/img/...' path with one resolved from __file__
so the script writes to the correct location regardless of cwd.

Also includes minor SVG whitespace normalization from mmdc 0.4.1 re-render
(stroke-width:3px vs stroke-width: 3px — functionally identical).

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

The previous approach used per-element inline style= attributes on the 15
figcaptions across the two tutorial docs files. That only covered existing
files — any future doc page with a figcaption would be unstyled.

Replace with a proper Laika-level fix:
- Add docs/src/helium/custom.css with the figcaption rule
- Wire it into the Helium theme via .site.internalCSS() in LaikaCustoms.scala
  (required in Laika 1.0+; the old automatic CSS directory scanning is gone)
- Strip the now-redundant inline style= attributes from both tutorial docs

The <style> block in the notebooks (Jupyter rendering) is unchanged — it
remains the correct mechanism for notebooks since they do not go through Laika.

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

…s/97K edges

Every mention of the ~130K nodes / ~97K edges figures now names the specific
Stack Exchange dataset (stats.meta.stackexchange.com) so readers know exactly
which archive produces those numbers.

Updated in:
- docs/src/03-tutorials/04-pregel-tutorial.md
- docs/src/03-tutorials/02-motif-tutorial.md
- python/graphframes/tutorials/notebooks/Pregel.ipynb (cell 2)
- python/graphframes/tutorials/notebooks/Network_Motif_Finding.ipynb (cell 0)

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>

<center> is a deprecated element that centers relative to its nearest
containing block. In Helium's layout that block spans the full page
(content column + both sidebars), so figures appeared shifted right.

Fix by:
- Adding figure { margin: 1em 0; text-align: center; } and
  figure img { max-width: 100%; height: auto; } to custom.css and
  the notebooks' <style> block — centering is now done via CSS
  within the content column's own containing block
- Removing all 30 <center>/<\/center> wrappers from the two tutorial
  docs and both notebooks; plain <figure> blocks are sufficient

Co-authored-by: Russell Jurney <rjurney@users.noreply.github.com>